Study Of Silk Protein Regulating The Morphology Of Zinc Oxide Matrix Composites And Gas Sensitivity Of Nitrogen Dioxide

With the development of social economy,our state pays more attention to the construction of ecological civilization,and has adopted many policies on national health.Nitrogen dioxide?NO₂?is one of the main pollutants in the environment,it is great significance to develop a low-cost and accurate gas sensor which can detect the concentration of that.Zinc oxide has N-type characteristics in P-type and N-type semiconductors,and its physical form is usually crystalline or powder.It has a low price,and is often used in chemical additives as well as in the preparation of gas sensors.Therefore,the gas sensor is mainly based on the zinc oxide matrix composites and the regulation of silk fibroin in this paper.The sensitivity and reproducibility of the system to nitrogen dioxide gas were studied.The main contents of this paper are as follows:1.Gas sensor materials with different mass ratios of ZnO,ZnO/SF?5:1?,ZnO/SF?10:1?and ZnO/SF?15:1?were successfully prepared by hydrothermal synthesis process.The effect of the ratio of silk protein to zinc oxide on the gas sensitivity was studied and the synthesis process was improved by ours.The sensitive characteristics of these sensors with different concentration of nitrogen dioxide gas were tested and analyzed by ours.The test results show that the sensitivity of ZnO/SF?10:1?gas sensor reaches 85 when detecting 20 ppm nitrogen dioxide.The average response recovery time of the gas is 26 s and 16 s,respectively.The fitting coefficient R2 is 0.9833,and the detection limit is 1 ppm in the range of 1 ppm to 20 ppm.The repeatability test results show that the response value of the gas sensor to nitrogen dioxide changes little,as a result,the sensor has good repeatability.Combined with the SEM and XRD images measured by scanning electron microscopy?SEM?and X-ray Diffraction?XRD?know the material of the composite material was pure.Silk protein plays a regulatory role in the synthesis process,and the appropriate proportion of the synthesized gas-sensitive materials can achieve the best performance.2.In₂O₃ was added on the basis of ZnO/SF by hydrothermal synthesis process.ZnO/In₂O₃/SF gas-sensing composites with different mass ratios were successfully prepared.The gas sensor with response is made by spraying method.The gas sensing performance of the prepared ZnO/In₂O₃/SF gas sensor with different mass ratios was tested under ultraviolet light.The test results show that the ZnO/In₂O₃/SF?10:1:1?gas sensor has good gas sensitivity to NO₂.When NO₂ gas is 30 ppm,the sensitivity of ZnO/In₂O₃/SF?10:1:1?gas sensor is 350.The average response recovery time was 34 s and 23 s,respectively.The sensitivity of ZnO/In₂O₃/SF?10:1:1?gas sensor has a good linear relationship with the concentration of NO₂ gas,and the linear coefficient R2 is 0.984.The results of nitrogen dioxide repeatability test show that the ZnO/In₂O₃/SF?10:1:1?gas sensor has good repeatability.But,the stability test shows that its stability performance is not very good.SEM and XRD analysis that the combination of zinc oxide and indium dioxide increases the surface area of the material and the gas attachment sites,thus increasing the gas sensitivity.